As disclosed in Patent literature 1, in an optical node of an optical communication network, in order to improve the reliability of a wavelength path that is a communication path, a dedicated standby system wavelength path is generally assigned to an operating system wavelength path. The same traffic as the operating system wavelength path is caused to pass through the standby system wavelength path, so that switching can be performed from the operating system wavelength path to the standby system wavelength path immediately at the wavelength path reception end when a failure occurs in the operating system wavelength path. As a result, the immediate failure recovery can be achieved to secure the reliability of the wavelength path.
Recently, the communication throughput for each wavelength path has been increased up to at an annual rate of 40%, and a demand for improvement of the reliability of a wavelength path has been increasing. As disclosed in Patent literature 2, in order to respond to the demand, the improvement of the reliability is achieved by assigning a plurality of standby system wavelength paths to the operating system wavelength path.